KR20110016594A - Moisture absorbent having self- and multi-indicating ability according to hygroscopic levels and preparing method thereof - Google Patents

Abstract

PURPOSE: A multi-stage self-indicating moisture absorbent, and a producing method thereof are provided to use the moisture absorbent as a desiccating agent or a humidifying agent. CONSTITUTION: A multi-stage self-indicating moisture absorbent contains 0.0005~0.5wt% of methyl violet, and 0.0005~7.5wt% of quinaldine red. The multi-stage self-indicating moisture absorbent additionally contains a self-multi indicator uniformly dispersed in the absorbent, and the balance of porous desiccant.

Description

Moisture Absorbent Having Self- and multi-indicating Ability According to Hygroscopic Levels and Preparing Method Thereof}

The present invention relates to a hygroscopic agent having a multi-stage self-indicator and a method for manufacturing the same, and more particularly, after coating or immersing an acid aqueous solution of a specific organic dye mixture solution as a multi-stage self-indicator in a moisture-proof deodorant such as silica (silica) It can be used for desiccating and / or humidifying which gives multi-stage self-directing ability so that the moisture absorbency of the absorbent can be confirmed relatively accurately by the multi-stage chromaticity change. A porous moisture absorbent and a method for producing the same.

Generally, a moisture absorbent or a moisture absorbent is introduced into a food packaging container or a medicine packaging container to adsorb moisture in an atmosphere inside the container, thereby keeping the produced product constant at a predetermined water content or lower during storage, distribution, or use. It is used for the purpose of preventing deterioration or deterioration, as well as maintaining freshness, flavor, or chewing feeling in a good initial state, or moisture-sensitive precision electricity such as semiconductor chips, printed circuit boards, or products containing them. It is widely used to protect electronics from moisture.

Typical absorbents include silica gel (SiO ₂ · H ₂ O), alumino-silicate beads or clays such as montmorillonite, zeolites as molecular sieves. (zeolite: Na ₁₂ AlO ₃ SiO ₂ 12XH ₂ O), activated carbon, calcium oxide (CaO), calcium sulfate (CaSO ₄ ), and the like have been used.

Here, silica gel is used most widely because it shows excellent adsorption amount, non-toxic and non-corrosive, no deliquescent, water-insoluble, easy to handle, inexpensive, and less likely to cause contamination problems.

Although montmorillonite is a bead type adsorbent made of magnesium aluminum silicate, it is generally easy to be powdered, and thus has a high risk of contamination and inferior water absorption ability compared to silica gel. However, montmorillonite has relatively low cost.

Zeolites have a reticulated micro-sphere structure and have a specific surface area of about 700 to 800 m2 / g. However, zeolites do not release moisture to the product in the package due to the increase in temperature such as silica gel or clay. There is a disadvantage of being expensive.

Activated carbon has a very large specific surface area of about 200 to 1200 m 2 / g, which is excellent in adsorption capacity, but is almost not used as a hygroscopic agent for normal use due to product contamination.

Calcium oxide is an annealing or recalcinated type lime that has a water adsorption capacity of 28.5 wt% or less and is mainly used for dehumidifying food packaging of refrigerated or frozen foods because it has moisture adsorption capability at very low relative humidity. It is used.

Calcium sulfate, commercially known as Drierite, is chemically stable, non-disintegrating, non-toxic and non-corrosive, and does not release moisture once adsorbed even at elevated temperatures, but has a water adsorption capacity of 10 wt%. There is only a disadvantage that is only used in a limited range.

Among the various moisture absorbents described above, silica gel is superior to other moisture absorbents in terms of performance and cost, and thus is widely used not only in the packaging of food, medicine, and various electronic products, but also in all industries, and has high purity amorphous silicon dioxide (SiO ₂ ) molecules. Silica gel is composed of a large specific surface area, no chemical change, no solubility, no corrosion, water insolubility, and the particles are transparent, hard and colorless and odorless due to the well-developed pore structure inside the particles. As it is harmless to human body, it has excellent adsorption power to moisture and gas, does not change after moisture absorption, has high water resistance when used for industrial use, and has high stability due to low crushing rate when contacted with water.

On the other hand, various moisture absorbents which have imparted moisture adsorption ability to the above moisture absorbents have been conventionally proposed. The moisture absorbent having the moisture adsorption indication removes moisture in the packaging of food or pharmaceutical packaging or precision electronics to maintain a dry state, and the color change occurs as the moisture absorption amount of the moisture absorbent increases. Moisture indicators for easy visual grasping of moisture adsorption or as humidity indicators in gas drying columns, or for dehumidification, protection and maintenance of transformer breathers, tank breathers or electrical and electronic telecommunication systems. It is widely used as a moisture-proof indicator in a desiccator of a laboratory, or as a desiccator in a laboratory, and the demand is expected to increase further with the diversification and quality of life.

As a typical hygroscopic agent having a conventional water adsorption indicator, a hygroscopic agent including a cobalt indicator has been widely used, for example, USP 2,460,071 (hygroscopic agent containing cobalt chloride), USP 2,460,069 (hygroscopic agent containing cobalt bromide), USP 2,460,073 ( Cobalt iodide containing moisture absorbents), USP 2,460,074 (cobalt sulfate containing moisture absorbents), USP 2,460,065 (cobalt sulfate containing moisture absorbents), USP 2,460,070 (cobalt phosphate containing absorbents), and the like.

Absorbents containing the cobalt indicators described above generally contain a minimum of 0.5wt% cobalt halide by impregnating a wetted silica gel or silica hydrogel in a cobalt halide solution, so that the color is blue to pink when water is absorbed. It is prepared in the form of a changing blue anhydrous granular gel.

However, cobalt halides, in particular cobalt chloride, have been classified in the European Union as category II carcinogens (EEC notification, 15/12/98), and as of the date of 2000.7.1 the new EU Directive (Directive 98/98 / EC) has been applied. Within the European Union, the manufacture and distribution of cobalt halides containing cobalt chloride and products containing them as potential carcinogens has been virtually banned, and this trend is spreading to other parts of the world.

In particular, in view of the fact that the injection target of silica gel as a moisture absorbent is food and medicine, it is expected that the use of cobalt halide worldwide will be banned in the near future in the future. The development of alternative hygroscopic indicators is called for.

Various prior arts have been proposed to replace cobalt halide containing humectants at the request of the art.

USP 2,460,072 and USP 2,460,067 disclose copper (II) chloride and copper (II) bromide, respectively, but these compounds are potentially toxic and are not environmentally and human-friendly and are therefore not intended for use in commercial food and pharmaceutical packaging. There is a problem that it is not suitable as a moisture absorbent.

In addition, "Indicator properties of vanadium-modified silicas and zeolites" (Belotserkovskaya et al., Zh. Prikl. Khim. (Leningrad), 63 (8), 1674-9), "Synthesis and study of physicochemical properties of vanadium-containing silica-a humidity indicator "(Malygin, AA, Sb. Nauch. Tr. VNII Lyuminoforov I Osobo Chist. Veshchestv, 23, 24-8) and" Study of properties of vanadium-containing silica gel "(Malygin, AA et al. , Zh.Prikl.Khim. (Leningrad), 52 (9), 2094-6) showed that the vanadium compound VOCl ₃ was colorless to yellow and then orange again with increasing humidity when impregnated with silica gel Next, it is reported that the color finally shows brown color change. However, VOCl ₃ has a serious problem of being corrosive and toxic and difficult to manufacture or handle.

In addition, Korean Patent No. 676,777 is a moisture absorbent for protecting a semiconductor chip or a printed circuit board, dissolving an indicator selected from thymol blue, methyl red, methyl orange, methyl red, neutral red, aniline blue in ethyl alcohol, Although a cobalt-free humidity indicator solution containing a soda solution, a deliquescent metal chloride and an organic polymer compound is proposed, there is a problem that it is not suitable for use in food or pharmaceutical containers because caustic soda and metal chlorides are included.

In addition to the above, methods for using various organic dyes and other inorganic compounds have been proposed to show chromaticity change with hygroscopicity as a conventional attempt to replace cobalt halides, in particular cobalt chloride, but these hygroscopic agents are safe. There is a problem that the indicator color is blue-based, and the indicator color indicating a red color does not show a color change similar to that of a conventional cobalt chloride-containing absorbent, which corresponds to an accident deeply imprinted on a general consumer and trader.

Specifically, as a moisture absorbent having a humidity indicator for replacing a cobalt chloride-containing absorbent, for example, the absorbent using phenolphthalein (discoloration point pH 8.3 to 10.0) changes color from yellow to colorless with increasing humidity. Hygroscopic agent using methyl orange (color change point pH 3.1 to 4.4), neutral red (color change point pH 6.8 to 8.0), thymol blue (color change point pH 6.0 to 7.6), or phenol red (color change point pH 6.8 to 8.4) It was not suitable as a hygroscopic agent having a humidity indication without rejection because it showed a change in chromaticity from red to orange.

In order to solve the above problems of the prior art, Korean Patent No. 894,629 by the present applicant proposes a hygroscopic agent containing methyl violet, which is harmless to the human body, environmentally friendly, has good sensitivity to moisture absorption, and exhibits stable indication. However, since the color due to moisture absorption is changed from blue to purple, the indicator color indicating danger is not satisfactory enough to satisfy the accidents deeply imprinted with the general consumer and trader of red, and if the relative humidity exceeds 30%, It is no longer enough to be used as a humectant because it can no longer detect a change in purple color itself, and it is difficult to use it as a humectant. By clear multi-stage chromaticity change over Indicating the degree of humidity is not possible value, so there is a problem that can be applied to the color card indicated for the absorption degree.

Therefore, the first object of the present invention is to provide a hygroscopic agent which is harmless to the human body and has environmentally friendly multi-stage self-directing ability.

The second object of the present invention is that the color indicates the danger as the color of the hygroscopicity changes from dark blue to purple, pinkish light purple, pink, light red, and finally dark red in multiple stages. The present invention is to provide a hygroscopic agent that has sufficient sensitivity to hygroscopicity and has a stable multi-stage self-indicating ability while being fully in line with an accident deeply imprinted on the conventional general consumer and trader of red.

It is a third object of the present invention to provide a pulp paper or a resin board or a color indicating card according to a degree of moisture absorption in which a hygroscopic agent having a multi-stage self-indicating ability according to the first and second objects of the present invention is applied.

A fourth object of the present invention is to provide an effective method for preparing a hygroscopic agent having multi-stage self-directing ability according to the first to third objects of the present invention described above.

According to one preferred embodiment of the present invention for smoothly achieving the first and second objects of the present invention, the content of methyl violet is 0.0005 to 0.5wt%, preferably based on the total weight of the composition. Preferably 0.01 to 0.2wt%, specifically 0.01 to 0.1wt%, the content of Quinaldine Red is 0.0005 to 7.5wt%, preferably 0.01 to 5.0wt%, specifically 0.1 to 3wt % And at the same time the methyl violet: quinaldine red is composed of a multistage self-indicator consisting of a mixture of 1: 1 to 15, preferably 1: 7.5 to 12.5 by weight, and a porous moisture absorbent forming a balance. There is provided an absorbent having a multi-stage self-indicator in which the self-indicator is homogeneously distributed on the surface of the porous absorbent.

According to another preferred aspect of the present invention for smoothly achieving the first and second objects of the present invention described above, there is provided a moisture absorbent having a multi-stage self-directing ability wherein the porous moisture absorbent is silica.

According to a preferred aspect of the present invention for smoothly achieving the third object of the present invention described above, 10 to 80 wt%, preferably 20 to 70 wt% of the hygroscopic agent having the above-described multi-stage self-indicating ability, but not particularly limited Is a multi-stage self molded or laminated on the surface of a pulp or resin board composed of 35 to 55 wt%, 20 to 90 wt% of pulp or synthetic resin, preferably 30 to 80 wt%, and particularly 45 to 65 wt%. A hygroscopic agent having an indication is provided.

According to a preferred embodiment of the present invention for smoothly achieving the fourth object of the present invention described above, (A) 0.0005 to 0.5wt%, preferably 0.01 to 0.2wt% of methyl violet based on the total weight of the composition. , Specifically 0.01 to 0.1 wt%, and quinaldine red 0.0005 to 7.5 wt%, preferably 0.01 to 5.0 wt%, specifically 0.1 to 3 wt%, and at the same time the above-described methyl violet: quinaldine A coating solution adjusted to pH 3.5-4.5, preferably 3.8-4.2 is prepared by dissolving a multi-stage self-indicator in which red is a weight ratio of 1: 1-15, preferably 1: 7.5-12.5, in an acid solution. Multi-stage self-indicating composition comprising (B) a coating step of homogeneously distributing or spray-coating a porous moisture absorbent in the coating solution above, and (C) a drying step of evaporating and removing the acidic solution. Room for desiccant with moisture It is provided.

According to another preferred aspect of the present invention for smoothly achieving the fourth object of the present invention described above, 10 to 80 wt%, preferably 20 to 70 wt% of the moisture absorbent having the above-described multi-stage self-indicating ability, Preferably, 35 to 55 wt%, 20 to 90 wt% of pulp or synthetic resin, preferably 30 to 80 wt%, and particularly 45 to 65 wt% are mixed, made of paper and dried to form a pulp paper or molded after melting the resin. There is provided a method for producing a hygroscopic agent having a multi-stage self-directing ability produced in the form of a resin board or laminated on the surface thereof.

The hygroscopic agent having the multi-stage self-directing ability according to the present invention exhibits good sensitivity and hygroscopicity indicating ability in the medium to weakly acidic region, so there is no fear of corrosion of the packaged product by the hygroscopic agent regardless of the color change, and is harmless to the human body and the environment. The indicator color indicates safety because the color of the absorbent varies in a number of different steps, depending on the degree of moisture absorption, from dark blue to purple, pinkish purple, pink, light red, and finally dark red. And the indicator color indicating red indicates a clear and stable indicator that is faithful to the accidents deeply imprinted on the general consumer and trader, which is red, and therefore, as an air conditioner for an environment where a dry condition of about 10% relative humidity is required. If a humid environment of around 50% relative humidity is required It can be made to function as a humectant, and can effectively replace the existing silica gel humectant using the existing harmful cobalt chloride-based indicator, optionally formed into the form of card pulp paper or resin board or the surface thereof. When used in a stacked form, there is no fear of user's carelessness or food contamination by infants or children, and there is no fear that children or infants may be mistaken for food and swallowed.

Hereinafter, the present invention will be described in detail.

The hygroscopic agent having a multi-stage self-indicator according to the present invention has a methyl violet content of 0.0005 to 0.5 wt%, preferably 0.01 to 0.2 wt%, and specifically 0.01 to 0.1 wt% based on the total weight of the composition. , The content of Quinaldine Red is 0.0005 to 7.5wt%, preferably 0.01 to 5.0wt%, specifically 0.1 to 3wt%, and at the same time the methyl violet: quinaldine red is 1: 1 in weight ratio It is composed of a multistage self-indicator consisting of a mixture of ˜15, preferably 1: 7.5 to 12.5 and a porous hygroscopic agent forming a balance, and the multistage self-indicator is homogeneously distributed on the surface of the porous hygroscopic by dipping or spray coating. .

As a hygroscopic indicator to be applied to the multi-stage self-directing hygroscopic agent according to the present invention, methyl violet, mauveine, tetrabromo phenol blue (Tetrabromo Phenol Blue) exhibiting a change in chromaticity from blue to red ), Bromothymol blue, litmus, etc., but the discoloration range of the indicator except for methyl violet is a neutral to weakly acidic or acidic region, there is a problem that the discoloration sensitivity is not sensitive when moisture absorption, Tests applied to Movane, Tetrabromo Phenolbulo, Bromothymolblue, and Litmus were found to be not satisfactory enough to show a distinct color change from the blue to the red color desired to be obtained from the chromatic change. In the case of blue (blue) to violet (purple), a sharp and vivid color change Since did appear, methyl violet were selected as primary heupseupji reagent in the present invention.

On the other hand, benzofurfurin and Congo are the second moisture absorption indicators for inducing a sharp and clear color change from violet (blue) to violet (purple), followed by a sharp and clear color change from violet to red (red). Various indicators are contemplated, such as red, methyl orange, and quinaldine red, but benzofurfurin and Congo red do not stain or color silica gel in the range of 0.005 to 0.5 wt% addition, specifically 0.005 to 0.05 wt%. It is difficult to apply due to poor coloration, and methyl orange has been found to have a problem in that coloration occurs in the above-described amount of addition but the change in color is unclear, whereas in the case of quinaldine red, the relative humidity exceeds 30%. From violet (purple) and methyl by methyl violet in steps up to 90% relative humidity It is deeply imprinted on the conventional consumer and trader that the indicator indicating safety is blue and the indication indicating risk is red, with a light gradation of light purple, pink, light red, and finally dark red. Quinaldine red was selected as the secondary hygroscopic indicator in the present invention because it faithfully met the accident and exhibited clear and stable indication.

A particularly unexpected surprise here is that when quinaldine red is used in combination with methyl violet in a weight ratio of methylviolet: quinaldine red = 1: 1-15, preferably 1: 7.5-12.5, Although it is an indicator that discolors from colorless to red, when used in combination with methyl violet, the relative humidity of methyl violet, which causes discoloration to violet (purple) up to about 30% relative humidity, is not affected at all, It overcomes the effect of methyl violet, which retains its violet color (violet) even when it is exceeded, and expresses a reddish shade of gradation from 30% to 90% relative humidity.

When the weight ratio of quinaldine red to methyl violet is less than 1, the tendency to maintain violet even at a relative humidity of 30% or more is increased due to the effect of methyl violet, and the gradual color change becomes unclear. If exceeded, the tendency to maintain red even at a relative humidity of 30% or less becomes stronger, so it is not preferable because the gradation change of color becomes unclear.

On the other hand, even if the weight combination ratio of methyl violet and quinaldine red satisfies the above range of 1: 1 to 15, when the addition amount is less than the above-mentioned range, the color tone becomes light, which is not preferable. If the range is exceeded, the color tone becomes too dark and becomes dark overall, which is also undesirable because it may be difficult to read the chromaticity change.

In the hygroscopic agent having a multi-stage self-indicator according to the present invention, the porous hygroscopic agent is silica, alumino-silicate, zeolite, montmorillonite, activated carbon carbon), calcium oxide (CaO), calcium sulfate (CaSO ₄ ), calcium chloride, or mixtures thereof, but are not intended to exclude them from the present invention, but preferably silica gel, alumino-silicate beads (aluminosilicate bead), zeolite (zeolite), and the most preferred is silica gel in consideration of stability and cost, as well as excellent as a function of the detergent as well as a detergent.

The porous moisture absorbent is 0.0005 to 0.5 wt%, preferably 0.01 to 0.2 wt%, specifically 0.01 to 0.1 wt%, and quindine red 0.0005 to methyl violet, based on the total weight of the composition. 7.5 wt%, preferably 0.01 to 5.0 wt%, specifically 0.1 to 3 wt%, and at the same time the mixture of methyl violet: quinaldine red described above in a weight ratio of 1: 1 to 15, preferably 1: 7.5 to 12.5 Multi-stage self-indicator according to the present invention by surface coating or depositing with an acidic solution such as ethanol aqueous solution adjusted to pH 3.5-4.5, preferably 3.8-4.2 in which the multi-stage self indicator is dissolved. Absorbents are prepared and exhibit a clearly discernible color change over the entire range of relative humidity.

On the other hand, when referring to the form of the moisture absorbent comprising a moisture absorbing indicator according to the present invention, although the powder form is possible, it is molded into a conventional bead shape with an average diameter of 20 ~ 3000㎛ and the breathable pack It can be used in a general form to accommodate, optionally, the above-mentioned moisture absorbent in the range of 0.5 ~ 200㎛ average diameter and then mixed with pulp or synthetic resin to form a pulp paper or resin board or laminated on the surface Can also be used as

In this case, the amount of the hygroscopic agent having the multi-stage self-indicating ability is 10 to 80 wt%, preferably 20 to 70 wt%, although not limited to 35 to 55 wt%, and the amount of pulp or synthetic resin is 20 to 90 wt%. It is preferably 30 to 80 wt%, and specifically 45 to 65 wt%.

A multistage self-directing hygroscopic agent according to the invention can be prepared via the following steps:

(A) 0.0005 to 0.5 wt% of methyl violet, preferably 0.01 to 0.2 wt%, specifically 0.01 to 0.1 wt%, and quinaldine red 0.0005 to 7.5 wt% based on the total weight of the composition. %, Preferably 0.01 to 5.0 wt%, specifically 0.1 to 3 wt%, and at the same time the methyl violet: quinaldine red described above is composed of a mixture of 1: 1 to 15, preferably 1: 7.5 to 12.5 by weight. Dissolving the multi-stage self indicator in an acid aqueous solution to prepare a coating solution adjusted to pH 3.5 to 4.5, preferably 3.8 to 4.2;

(B) coating step of homogeneous distribution on the surface of the porous absorbent by dipping or spray coating the porous absorbent in the coating solution; And

(C) a drying step of evaporating and removing the acid solution.

In the step (A) described above, an acid is added to an aqueous solution of an organic dye indicator of methyl violet and quinaldine red to prepare an aqueous acid solution (hereinafter referred to as "coating liquid") adjusted to pH 3.5 to 4.5, preferably 3.8 to 4.2. .

The acid for preparing the above-mentioned acid aqueous solution is not particularly limited as long as it can be used with a selected organic dye indicator to form an acid of the aqueous solution, but is preferably ethyl alcohol, acetic acid, phosphoric acid, tartaric acid, succinic acid, citric acid, maleic acid. , Or fumaric acid alone or a mixed solvent thereof may be used.

Here, suitably, a coating aid may be included in the acid solution so that the acid solution of the organic dye indicator can be wetted evenly with the porous moisture absorbent. Examples of the coating aid include, for example, alcohols, In particular, although ethyl alcohol may be included, the present invention is not limited thereto, and any polar solvent which may help to improve coating dispersibility and does not react with a moisture absorption indicator is not particularly limited.

In the step (B) described above, the coating solution is wetted on the surface of the porous absorbent by dipping or coating the porous absorbent in the acid aqueous solution prepared above. Immersion or coating can generally be carried out at room temperature.

In addition, in the step (B) described above, a porous moisture absorbent saturated with steam may be used to avoid a phenomenon of splashing during impregnation or coating of the porous moisture absorbent. The particle size decreases slightly when the porous absorbent is directly immersed or coated in the coating solution.

In the above (C) step, the coating solution is wet with the absorbent, and then dried, and dried at about 200 ° C. or less for 1 to 10 hours.

On the other hand, if the moisture absorbent during use to change the color of the absorbent is restored to its original state when re-dried, it retains the hygroscopicity indicator that can be reused.

It is important to adjust the pH of the acid aqueous solution as the coating solution adjusted to pH 3.5-4.5, preferably pH 3.8-4.2 by adding acid to the aqueous solution of the organic dye indicator of methyl violet and quinaldine red in the above, The reason is that the above pH range is useful for the moisture absorbent to slightly lower the sensitivity of methyl violet and to increase the sensitivity of quinaldine red when the moisture is absorbed, and if the silica gel is less than the acidic zone, regardless of the color change, the package or package This is because the silica gel is more preferably in the middle acid range or more because of the possibility of corrosion when having corrosiveness.

The porous moisture absorbent having a multi-stage self-indicator according to the present invention prepared as described above has a moisture absorption indicator in the neutral acid region or more, and from blue to purple while changing from the acidic region to the neutral region according to the moisture absorption amount, A distinctive chromaticity change occurs in multiple stages: pinkish purple, pink, light red, and finally dark red.

In the case of the hygroscopic agent manufactured in various forms and properties such as silica gel, the point of change of chromaticity can be optimally controlled by precisely adjusting the pH and the amount of indicator of the organic dye indicator aqueous solution (methyl violet and quinaldine red aqueous solution) according to the physical properties. Of course.

The hygroscopic agent with multi-stage self-indicative according to the present invention shows a visually identifiable chromaticity change at a relative humidity of 10% or more. Because of the difference in shades, it can be sufficiently identified. When a combination of methyl violet and quinaldine red is used as the organic dye indicator, it is particularly preferable to apply it as a chromaticity indicator card because it gradually changes from violet (purple) to red (red) when absorbed in blue when dried.

On the other hand, the hygroscopic agent having a multi-stage self-indicator according to the present invention may be prepared in the form of pulp paper or resin board or laminated on it, as described in Korean Patent No. 894,629. In this case, the content of the absorbent is not limited, but is 10 to 80 wt%, preferably 20 to 70 wt%, and specifically 35 to 55 wt%, and the content of pulp or synthetic resin is not limited but 20 to 90 wt% based on dry weight. Preferably 30 to 80 wt%, and particularly 45 to 65 wt%.

When produced in pulp paper form or laminated thereon, the pulp paper as a backing substrate may be a smooth paper or a pulp mold.

When the pulp paper is a general smooth paper, the following steps may be further performed.

(D1) The moisture absorbent coated with the moisture absorption indicator via step (B) described above is sprayed onto a smooth paper coated or attached with an adhesive layer or a double-sided adhesive tape on at least a part of the area on at least one surface (spraying on the adhesive layer) step). Subsequently, (D2) the drying layer is transferred to a drying booth, for example, by drying means such as a hot air tube, an infrared heater, etc., and then dried at 200 ° C. or lower, preferably 70 to 80 ° C. for 0.5 to 4 hours, thereby curing the adhesive layer and By drying, the moisture absorbent is permanently fixed on the smooth paper (curing and drying step). Optionally (D3) the masking means is removed if a masking treatment for a specific pattern is performed. (D4) The excess moisture absorbent not adhered to the smooth paper is then swept off by brush roller or air blowing (e.g., air cleaning for 30-50 seconds at an air pressure of 5-7 kbar) and then recovered with a recovery hopper ( Cleaning step).

The kind of the adhesive layer is not particularly limited as long as it can faithfully perform the role of permanent fixation, but may be any of those based on an aqueous acrylic copolymer or a polyurethane-based polymer, and cationic commonly used in the field of binders. , Anionic or nonionic pigments, wax oils and the like. In addition, although the above-mentioned hardening thickness of an adhesive layer is not restrictive and arbitrary in this invention, it is generally 30-300 micrometers thick, Preferably it is 50-150 micrometers thick, More preferably, it is 90-120 micrometers thick.

When the pulp paper is a pulp molding, the following steps may be further performed.

(E1) performing the step of mixing and papermaking the absorbent coated with the hygroscopic indicator via step (B) above and dissociated into the dissolved pulp liquid, and then (E2) transferring it to a drying booth and drying means as described above. By means of drying at 200 ° C. or lower, preferably 70 to 80 ° C. for 0.5 to 4 hours, or drying at room temperature for 1 to 2 days to obtain a pulp molded product in which a moisture absorbent is fixed in a pulp molded product formed into smooth paper or a specific shape. .

In addition, in the case of manufacturing in the form of a synthetic resin board or laminated thereon, (F1) melted synthetic resin such as polyethylene, polypropylene, polyurethane, etc. Spray an absorbent with a moisture absorbent (dehumidifier spraying step) and (F2) to harden to fix the absorbent on at least one surface of the board (curing step), or optionally (G1) molten polyethylene, polypropylene, poly A moisture absorbent including a moisture absorbent indicator via the above step (B) may be mixed with a synthetic resin such as urethane (hygroscopic mixing step), (G2) extrusion molding onto a board and a curing step (molding step).

The thickness of the above pulp paper or resin board is not limited in the present invention, but may be about 0.1 to 0.5 mm in thickness.

In addition, when the multi-stage self-indicating absorbent according to the present invention is applied to a multi-stage chromaticity indicator card, the color of the chromaticity color photo at the relative humidity of each step is printed as a standard on a strip-shaped card as a part of another area. By coating or adhering the moisture absorbent according to the present invention, it is possible to grasp the relative humidity under a specific atmosphere relatively accurately by contrasting the chromaticity change with the above standard.

The hygroscopic agent having a multi-stage self-indicator according to the present invention can be applied as a drying agent (drying agent) to a product packaging environment requiring a dry state of about 10% relative humidity, in particular, less than 10% relative humidity. Of course, it can be made to function as a humectant in the case of succulent food packaging that requires a moist environment of about 50% or more.

Hereinafter, the present invention will be described in more detail with reference to Examples, Comparative Examples and Test Examples, which are intended to illustrate the present invention, but are not intended to limit the scope of the present invention. Nor is it.

Example 1 Preparation of a Hygroscopic Agent Having Multi-Stage Self-Indicating Capacity

Methyl violet and quinaldine red were used as a hygroscopic indicator in porous silica gel having an average particle diameter of 1800 μm. Silica gel was immersed in a solution consisting of 0.1 wt% of methyl violet, 1 wt% of quinaldine red, and 5 wt% of alcohol at room temperature to be wetted, and then dried at 150 ° C. for 2 hours 30 minutes.

When the silica gel absorbent was dried, the absorbent changed from dark blue (dark blue) to violet (purple) and pink (pink) light purple, pink, light red, and finally dark red.

The result is shown in FIG. 1 and the case where only methyl violet was used without addition of quinaldine red as a control is shown in FIG.

Comparative Example 1 Preparation of a Hygroscopic Agent Containing Methyl Violet and Benzofurfurin

A hygroscopic indicator was prepared by combining methyl violet and benzopurpurin (coloring from blue to red in solution state; inflection point pH 1.3 to 5) on porous silica gel having an average particle diameter of 1800 μm. Silica gel was immersed at room temperature in a solution composed of 0.05 wt% methyl violet, 0.05 wt% benzofurfurin, and 5 wt% alcohol, followed by drying at 150 ° C. for 2 hours and 30 minutes.

Benzofurfurin was not colored on silica gel.

Comparative Example 2: Preparation of Methyl Violet and Congo Red-Based Hygroscopic

A hygroscopic indicator was prepared by combining methyl violet and Congo red (purple to red in solution state; inflection point pH 3.0 to 5.2) on porous silica gel with an average particle diameter of 1800 μm. Silica gel was immersed in a solution composed of 0.05 wt% methyl violet, 0.05 wt% Congo red, and 5 wt% alcohol at room temperature to be wet, and then dried at 150 ° C. for 2 hours 30 minutes.

Congo red was not colored on silica gel.

Comparative Example 3: Preparation of Hygroscopic Agent Containing Methyl Violet and Methyl Orange

A hygroscopic indicator was prepared by combining methyl violet and methyl orange (colored from red to yellow; inflection point pH 3.0 to 4.4) on porous silica gel with an average particle diameter of 1800 μm. Silica gel was immersed at room temperature in a solution composed of 0.05 wt% methyl violet, 0.05 wt% methyl orange, and 5 wt% alcohol, followed by drying at 150 ° C. for 2 hours and 30 minutes.

Although methyl orange was colored on silica gel, the color change due to methyl orange itself was not clear due to the dark violet effect of methyl violet.

Example 2: Preparation of Hygroscopic Pulp Paper

The moisture absorbent having the multi-stage self-indicative prepared in Example 1 was sprayed onto a pulp paper coated with an epoxy adhesive layer on a part of the surface, dried at 150 ° C. for 2 hours and 30 minutes to cure the adhesive layer to form a specific pattern. The moisture absorbent was sufficiently dried while being permanently fixed to pulp paper. The weight of the moisture absorbent was 51 wt% and the weight of the pulp paper was 49 wt%.

The pattern of the pulp paper was changed to purple, pinkish purple, pink, light red, and finally dark red as the moisture absorption increased in blue.

Example 3: Preparation of Hygroscopic Pulp Paper (Pulp Molded Product)

A multi-stage self-indicating hygroscopic agent (50 wt% based on dry weight) prepared in Example 1 was mixed with kraft pulp solid solution (50 wt% based on dry weight) and papermaking to prepare a smooth pulp molding having a thickness of 2 mm. It dried at 2 degreeC for 2 hours and 30 minutes, it was made to paper-board, and the said moisture absorbent was fixed in the pulp molding, and the moisture absorbent was fully dried.

The pulp molded product was changed in several stages from purple to pinkish purple, pink, light red, and finally dark red as the hygroscopic progressed from blue.

Example 4 Preparation of Hygroscopic Synthetic Resin Board

The moisture absorbent having the multi-stage indicator prepared in Example 1 was sprayed onto a synthetic resin board coated with an epoxy adhesive layer on a part of the surface, dried at 110 ° C. for 2 hours and 30 minutes to cure the adhesive layer to pulp the absorbent beads into a specific pattern. The moisture absorbent was sufficiently dried while being permanently fixed to the paper. The weight of the absorbent was 38wt% and the weight of the synthetic resin was 62wt%.

The pattern on the synthetic resin board was changed in several stages from purple to pinkish purple, pink, light red, and finally dark red as the moisture absorbed from blue to dry.

Example 5 Preparation of Hygroscopic Synthetic Resin Board

A hygroscopic indicator coated with a moisture absorbent prepared in Example 1 (20wt% on a dry weight basis) is mixed with polyethylene resin (80wt% on a dry weight basis), melted, and extruded to prepare a synthetic resin board having a thickness of 1.5 mm. It dried at 2 degreeC for 2 hours and 30 minutes, and fixed the moisture absorbent in the polyethylene resin board, and dried the moisture absorbent sufficiently.

As the polyethylene resin board was dried, the hygroscopic progressed from blue to purple, pinkish purple, pink, light red, and finally dark red.

Example 6 Preparation of Hue Instruction Card

The absorbent having the multi-stage self-indicator prepared in Example 1 was color photographed at a relative humidity of 0%, 20%, 40%, 50%, 60%, and 90%, and printed on transfer paper as a standard, followed by pulp. Transferring and pasting the above-mentioned transfer paper on one surface of the paper strip, apply an epoxy adhesive layer on one region not attached to the transfer paper, apply by spraying the above-mentioned moisture absorbent, and then dry at 150 ° C. for 2 hours 30 minutes to cure the adhesive layer. The moisture absorbent beads were permanently fixed on a part of the pulp paper surface to form a measurement unit, and the moisture absorbent was sufficiently dried.

The relative humidity in the gaseous atmosphere in the specific region could be measured by comparing the chromaticity of the measurement unit of the manufactured chromaticity indicating card with the color photograph in the relative humidity of each step described above.

Test Example: Changes in Hygroscopicity and Chromaticity According to Relative Humidity

The moisture content change and chromaticity change of the absorbent according to the relative humidity change of the absorbent having the multi-stage self-indicative of Example 1 were measured and observed, and the results are shown in Table 1 below, and specific chromaticity changes are shown in FIG. 1. Please.

Relative Humidity (%) 10 20 40 50 60 90 Silica gel
Moisture content (%) 6.8 11.0 17.8 29.5 34.2 42.0 color Blue black Progressive Mauve Light pink Light red peony

In addition, in the case of Examples 1 to 5, when the hygroscopic agent causing the color change was re-dried at 150 ° C. for about 2 hours and 30 minutes, it was again reduced to the original dark blue color.

1 is a photograph showing the change in chromaticity for each relative humidity of the absorbent having a multi-stage self-directing ability according to the present invention prepared in Example 1.

Fig. 2 is a photograph showing the change in chromaticity at 3% and 30% relative humidity when only conventional methyl violet is used.

Claims (8)

Methyl violet is 0.0005 to 0.5 wt% based on the total weight of the composition, and quinaldine red is 0.0005 to 7.5 wt%, and methyl violet: quinaldine red is 1: 1 to 15 by weight. Self- and multi-indicator and balance of the mixture consists of a porous absorbent, The multi-stage self indicator is homogeneously distributed in the porous moisture absorbent Hygroscopic agent with multi-stage self-directing ability. The hygroscopic agent according to claim 1, wherein the multistage self indicator is a mixture of methyl violet: quinaldine red in a weight ratio of 1: 1 to 15. The moisture absorbent according to claim 1 or 2, wherein the porous moisture absorbent is silica. The hygroscopic agent according to claim 1, wherein the hygroscopic agent having the multi-stage self-indicating ability is composed of pulp paper, synthetic resin board, or chromaticity indicating card. 5. The hygroscopic agent according to claim 4, wherein the weight of the pulp or the synthetic resin of the hygroscopic agent having the multi-stage self-indicating point is 20 to 90 wt%. Method for preparing a hygroscopic agent having a multi-stage self-indicator consisting of the following steps: (A) 0.0005 to 0.5 wt% of methyl violet and 0.0005 to 7.5 wt% of quinaldine red, based on the total weight of the composition, and methyl violet: quinaldine red in a weight ratio of 1: 1 to Preparing a coating solution adjusted to pH 3.5-4.5 by dissolving a multi-stage self indicator comprising a mixture of 15 in an acid aqueous solution, (B) coating step of homogeneous distribution on the surface of the porous moisture absorbent by dipping or spray coating the porous moisture absorbent in the coating solution, and (C) a drying step of evaporating and removing the acid solution. The method for producing a hygroscopic agent having multistage self-indicating ability according to claim 6, wherein the solvent used for the preparation of the aqueous acid solution is ethyl alcohol. 7. The method of claim 6, wherein the porous moisture absorbent is silica.

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